In recent years, an optical device such as a cell phone is structured on which an optical unit for photographing is mounted. In the optical unit, in order to restrain or reduce any disturbance of a photographed image due to a shake in the hand of a user, a technique has been proposed in which an angular velocity sensor, a photo reflector and a shake correction drive mechanism are disposed around a lens and, on the basis of a detection result for a shake by the angular velocity sensor, the shake correction drive mechanism is controlled and the position of the lens is monitored by the photo reflector (see Patent Literature 1).    [PTL 1] Japanese Patent Laid-Open No. 2002-207148
However, like the structure described in Patent Literature 1, when the photo reflector and the shake correction drive mechanism are disposed around the lens, a size in a direction intersecting an optical axis direction becomes extremely large. This problem is not limited to a case that a shake of hand is corrected in an optical unit for photographing and is common to a case that a shake is corrected in an optical unit.